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Troubleshooting Capillaries

Troubleshooting Expansion Valves

Troubleshooting Capillaries

Problem: Cap tube malfunction due to being partially or completely restricted.

Conditions that effect cap tube performance are:

Symptom: 

1. Low Suction

2. Starved Evaporator

Causes:

1. Refrigerant shortage

2. Too much oil in circulation

3. Low head pressure

4. Plugged drier

Symptom:

1. Flooding

2. Increased suction pressure

Causes:

1. High head pressure

2. Excessive sub cooling

3. Refrigerant overcharge

Troubleshooting Expansion Valves

Common Problems:

1. Flooding (overfeeding)

2. Starving (underfeeding)

3. Hunting (Erratic)

Flooding

Symptom:  No Superheat

Causes:

1. Valve sticking in open position

2. Improper superheat setting on valve

3. Improper valve bulb location

4. Wrong type of valve for refrigerant used

5. loose expansion valve bulb

6. Light load

7. Excess oil in system

Starving

Symptom: High Superheat

Causes:

1. Valve sticking in closed position

2. Loss of charge in power element

3. Wrong type of valve for refrigerant used

4. Refrigerant under charge

5. Improper superheat setting on valve

6. Plugged drier

7. Plugged Refrigerant distibutor

8. Improper valve bulb location

9. Plugged equalizer line